Salah Abdeslam, the key suspect in the Paris attacks arrested on Friday, showed little sign of religious fervour before the assaults and was even known to enjoy a beer and a joint in the bar he ran with his brother in the Brussels district where he was captured.

The 26-year-old Franco-Moroccan, whose brother Brahim blew himself up in the French capital during the November 13 attacks, is said to have fled into the arms of the Islamic State (IS) group in Syria but he was eventually tracked down to Molenbeek, the immigrant neighbourhood where he had lived for years.

But far from being religious fanatics, Salah and Brahim were known to enjoy a drink and some pot in Les Beguines, the bar they ran in Molenbeek.

File image of Salah Abdeslam. AFP

The bar was shut down two weeks before the Paris attacks after police said it was used "for the consumption of banned hallucinogenic substances".

A Molenbeek resident, who identified himself only as Youssef, told AFP last year the brothers were "friends of ours, big smokers, big drinkers, but not radicals".

Salah certainly knew radicals though, having come into contact with another Molenbeek resident, Abdelhamid Abaaoud, who is believed to have been the mastermind of the Paris attacks.

Salah was fired from his job as a technician on the Brussels trams for skipping work in 2011. Around the same time he was arrested for robbery along with Abaaoud.

Salah also developed a taste for casinos, gambling in the Dutch city of Breda in June 2014 and in Brussels last year.

But in 2015, in a possible phase of preparation for the Paris attacks, he criss-crossed Europe, visiting Greece in August, then Austria and Hungary, at a time when tens of thousands of migrants were transiting Europe from Syria and Iraq.

A routine search in Brussels earlier in the week went wrong and four Belgian police were wounded in an exchange of fire.

That led to Belgian police killing an Algerian, Mohamed Belkaid, an Algerian who had been with Salah in Austria in early September.

Belgian prosecutors announced Friday that Salah's fingerprints were found in the apartment they had been searching. Several hours later, he was arrested with two other men after shots were fired and Abdeslam was hit in the leg.

In charge of logistics

It was not just his disappearance that made Salah the enigma of the Paris attacks.

Prosecutors believe he was in charge of logistics for the attacks, which were planned in Brussels.

Salah rented the cars that the IS team used to travel to Paris, and booked the apartment-hotel rooms where they stayed before launching the worst ever terror attacks on French soil.

His brother Brahim, with whom he ran the Brussels bar, detonated his suicide vest in a bar in Paris on November 13, as at least eight other IS attackers were shooting and blowing up 130 people who had been enjoying a Friday night out in the French capital.

It is possible Salah drove three suicide bombers to the Stade de France stadium and he appears to have also been in central Paris where his accomplices where carrying out their slaughter.

But the evidence suggests he backed out of detonating his own suicide vest.

An explosives vest was founded abandoned in a dustbin in a Paris suburb and although none of Salah's DNA was found on it, mobile phone data puts him in the area at the time.

Before police were alerted to his possible involvement, Salah had been stopped three times by officers in France as he fled back to Belgium by car the day after the attacks.

Two men with him in the vehicle, Hamza Attou and Mohammed Amri, are said to have been smoking marijuana but a policeman waved them on and Salah was able to remain on the run for 126 days.